• Information and Communications Magazine
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• v.29 no.5
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• pp.3-9
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• 2012

본 논문에서는 재난 통신 및 네트워크 기술 그리고 앞으로의 발전 방향에 대해서 소개 하고자 한다. 제 1장에서는 주요 공공재난안전통신 기술들을 소개한다. 특히 동적 그룹통신기술(Push-To-Talk), 망 복구 및 생존성 향상 기술, 긴급호 구현 기술을 소개하며 또한 재난통신기술 표준화 필요성에 대해서 간단히 설명한다. 제 2장에서는 국내외 재난통신기술 동향을 살펴본다. 특히 미국, 유럽, 아시아에서 사용하는 주파수 대역 및 협대역 및 준광대역 주파수 공용 무선통신 기술인 TETRA(Terrestrial Trunked Radio), iDEN(Integrated Digital Enhanced Network) 및 APCO-P25(Association of Public Safety Communications Officials - Project 25)에 대해서 다룬다. 제 3장에서는 재난대비 미래 광대역 통신체계에 대해서 설명하며 마지막으로 제 4장에서는 본 논문의 결론을 맺는다.

• 한국공간정보시스템학회:학술대회논문집
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• 2005.11a
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• pp.141-146
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• 2005

최근 들어 텔레매틱스 분야에서 자동차의 위치 및 상태를 감시하고 관리하기 위해 무선 센서 네트워크의 활용이 크게 확장되고 있다. 기존에는 위치, 속도, 온도와 같은 이 기종 플랫폼간의 센서 데이타 수집 및 운용을 위해 독립적인 어플리케이션을 사용하고 있으며, 그러한 데이타 교환과 통합을 위하여 많은 비용이 소요되었다. OGC(OpenGIS Consortium)에서는 이러한 문제를 해결하고자 Sensor Collection Service 구현 명세를 제안하였다. Sensor Collection Service 구현 명세는 센서 데이타에 대한 질의를 처리하기 위한 표준 인터페이스를 정의하고 있으며, 질의 결과로는 센서에 대한 정보 및 센서데이타를 반환하도록 정의하고 있다. 본 논문에서는 Sensor Collection Service 표준 인터페이스를 이용하여 센서로부터 획득된 위치 및 속도, 온도 등의 다양한 데이타에 웹을 통하여 접근할 수 있도록 센서 데이타 서비스 시스템을 설계 잊 구현하였다. 따라서 사용자들은 센서 데이타 서비스 시스템을 통하여 센서의 종류와 위치에 관계없이 웹 상에서 위치 및 속도, 온도 등과 같은 다양한 센서 데이타를 획득할 수 있으며 시스템간 데이타의 교환 및 통합이 가능하다. 또한, 사용자가 쉴게 검색 및 분석할 수 있도록 Sensor Collection Service 표준 인터페이스 질의를 통하여 획득된 데이타를 센서의 위치와 측정 시간에 기반하여 보여주고 있다. 본 시스템은 다양한 센서 데이타의 획득과 타 시스템과의 데이타 교환이 용이하므로 텔레매틱스, 위치 추적 시스템, 상태 감시 시스템 등 다양한 분야에 효과적인 도구로 활용될 수 있다.이루어졌다 가능한 창조 모델로 이용될 수 있을 것으로 생각된다.}94,\;29.4{\pm}30.3,\;45.1{\pm}44$로 Mel 10군과 Mel 30군이 유의적인 감소를 보였으나(p<0.05) 이들 두 군 간의 차이는 나타나지 않았다. 이상의 결과로, 랫트에서 복강수술 후 melatonin 10mg/kg투여가 복강 내 유착 방지에 효과적이라고 생각된다.-1}{\cdot}yr^{-1}$로서 두 생태계에 축적되었다.여한 3,5,7군에서 PUFA 함량이 증가한 반면, SFA 함량은 감소하여 P/S 비율, n-3P/n-6P 비율은 증가하는 경향이었으며 이는 간장의 인지질, 콜레스테롤 에스테르, 총 지질의 지방산조성에서도 같은 경향을 볼 수 있었다.X>$(C_{18:2})$와 n-3계 linolenic acid$(C_{18:3})$가 대부분을 차지하였다. 야생 돌복숭아 과육 중의 지방산 조성은 포화지방산이 16.74%, 단불포화지방산 17.51% 및 다불포화지방산이 65.73%의 함유 비율을 보였는데, 이 중 다불포화지방산인 n-6계 linoleic acid$(C_{18:2})$와 n-3계 linolenic acid$(C_{18:3})$가 지질 구성 총 지방산의 대부분을 차지하는 함유 비율을 나타내었다.했다. 하강하는 약 4일간의 기상변화가 자발성 기흉 발생에 영향을 미친다고 추론할 수 있었다. 향후 본 연구에서 추론된 기상변화와 기흉 발생과의 인과관계를 확인하고 좀 더 구체화하기 위한 연구가 필요할 것이다.게 이루어질 수 있을 것으로 기대된다.는 초과수익률이 상승하지만, 이후로는 감소하므로,

• Journal of Industrial Convergence
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• v.21 no.3
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• pp.171-179
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• 2023

To investigate the effects of type of exercise on inflammatory factor and vascular endothelial growth factor in middle aged women, we recruited 18 people middle-aged women and they divided into 3 groups (N=6, resistance exercise group, 40-60% of 1RM, N=6 aerobic exercise group, 60-70% of VO2max, N=6, flexibility exercise group, 10-60 sec/sets). The data were compared to the effect of exercise between 50 ~ 60 minutes per a day, 3 day times per week on the body composition, inflammatory factor, vascular endothelial growth factor and vascular compliance in middle aged women. First, in regards to inflammatory factors between groups, a significant difference (p<.05) was identified in the effects of CRP and IL-6 in terms of time (T). Second, regarding vascular endothelial growth factors between groups based on the type of exercise, a significant difference (p<.05) was found in the effects of VEGF's time (T) and the interaction between time and group (TxG). In conclusion, All types of exercise could partially improve inflammatory factors and vascular endothelial growth factors.

• Journal of the Korean Society of Earth Science Education
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• v.17 no.2
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• pp.168-180
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• 2024

In this study, we developed a STEAM program based on digital astronomical and space resources and applied it to 167 randomly selected elementary school students to examine the effectiveness of the STEAM program in enhancing creative problem solving skills. The results of this study are as follows: first, the statistical analysis of pre-test and post-test scores for creative problem-solving skills related to the STEAM program showed significant results (p<.05). This suggests that the STEAM program contributed to improving creative problem-solving skills through the procedural process involved in generating ideas and convergent thinking during the digital problem-solving. Second, the paired sample t-test based on the pre-test and post-test of the STEAM attitude test also showed significant results (p<.05). Analyzing digital materials and presenting pixel art projects positively influenced STEAM attitudes in terms of interest, communication, and usefulness. This underscores the need for developing integrative education programs utilizing advanced technologies in the future. Third, in the class satisfaction test conducted after the application of the STEAM program, the satisfaction factor scored an average of 3.55, interest scored 3.35, and overall class difficulty scored 3.46. The main difference from traditional classes was the focus on 'acquisition of future career information.' However, given the slight decrease in interest during the digital transformation and interpretation process, it is recommended that future classes allocate sufficient time for experiential activities. To generalize the developed program, future studies should consider various school levels, implementation periods, and difficulty levels.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.3
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• pp.91-99
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• 2009

Development of high-speed Internet services and the increased supply of mobile devices have become the key factor for the acceleration of ubiquitous technology. WiBro system, formed with lP backbone network, is a MBWA technology which provides high-speed multimedia service in a possibly broader coverage than Wireless LAN can offer. Wireless telecommunication environment needs not only mobility support in Layer 2 but also mobility management protocol in Layer 3 and has to minimize handover latency to provide seamless mobile services. In this paper, we propose a fast cross-layer handover scheme based on signal strength prediction in WiBro environment. The signal strength is measured at regular intervals and future value of the strength is predicted by Exponential Smoothing Method. With the help of the prediction, layer-3 handover activities are able to occur prior to layer-2 handover, and therefore, total handover latency is reduced. Simulation results demonstrate that the proposed scheme predicts that future signal level accurately and reduces the total handover latency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.7A
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• pp.702-709
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• 2008

This paper presents a frequency offset estimation scheme which can be used for packet based OFDM communication systems. The proposed scheme detects the failure of performing coarse frequency offset estimation and compensates the error of estimated coarse frequency offset. The preamble structure considered in this paper is based on the preamble specified in IEEE802.11a and IEEE802.11p standards. We performed simulation to compare the performance according to the different number of reference packets used to detect the failure of performing coarse frequency offset estimation. The simulation results show that the proposed scheme has better performance than the conventional scheme in the low SNR(below 2dB) environment.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.49 no.6
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• pp.35-40
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• 2012

This paper has proposed a 3~5 GHz IR-UWB low power transmitter for range detection application. Proposed transmitter which has been implemented in a $0.13{\mu}m$ CMOS technology is all digital circuit that consist of simple digital logic. this feature insure low complexity and low power consumption. In addition, center frequency can be changed by adopting voltage controlled delay cell for avoiding existing another radio frequency in UWB low band. Proposed circuit consume only 10pJ/b from 1.2 V supply voltage. The simulation results show 3.3~4.3 GHz center frequency controllability, -51 dBm/MHz maximum output power and is satisfied with FCC regulation.

• Journal of Industrial Convergence
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• v.22 no.9
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• pp.63-68
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• 2024

In this study, This study is to explain the effects of body composition and blood vessel stiffness in middle-aged women according to exercise types. 16 middle-aged women were randomly assigned to group A (40~60% of 1RM) in the resistance exercise group and 8 in group B (VO2max 60~70%) in the aerobic exercise group, 3 times a week (monthly) for 12 weeks., Wednesday, Friday) As a result of comparison and analysis to determine the effect of 40 to 60 minutes of exercise per day on body composition, ABI, and PWV, the main effect of period on R-PWV, LPWV on vascular stiffness during aerobic exercise A significant difference (p<.05) was found. Based on the results of this study, it will be meaningful to study various angles of inflammatory factors and vascular endothelial growth factors according to exercise shape and to increase the number of follow-up cases, and it is expected to be used as basic data for improving blood vessel-related indicators of middle-aged women.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.689-692
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• 2005

In this paper, we have developed a retrodirective active array operating in the 2 GHz LS band. The retrodirective array has the property of re-directing any electromagnetic wave back to the incoming direction without any priory informations. The system is consisted of frequency mixers and antenna array. The mixer is acting as a phase conjugator. In this research, 2-port gate mixers using pHEMT and 1${\times}$4 monopole array have been used. The retrodirective array developed in this research can be applied in the base station facilities for the wireless mobile communications and RFID transponders.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.9
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• pp.868-882
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• 2009

In this paper, channel model and wireless link performance analysis for the short-range wireless communication system applications in the terahertz frequency which is currently interested in many countries will be described. In order to realize high data rates above 10 Gbps, the more wide bandwidths will be required than the currently available bandwidths of millimeter-wave frequencies, therefore, the carrier frequencies will be pushed to THz range to obtain larger bandwidths. From the THz atmospheric propagation characteristics based on ITU-R P.676-7, the available bandwidths were calculated to be 68, 48 and 45 GHz at the center frequencies of 220, 300 and 350 GHz, respectively. With these larger bandwidths, it was shown from the simulation that higher data rate above 10 Gbps can be achieved using lower order modulation schemes which have spectral efficiency of below 1. The indoor propagation delay spread characteristics were analyzed using a simplified PDP model with respect to building materials. The RMS delay spread was calculated to be 9.23 ns in a room size of $6\;m(L){\times}5\;m(W){\times}2.5\;m(H)$ for the concrete plaster with TE polarization, which is a similar result of below 10 ns from the Ray-Tracing simulation in the reference paper. The indoor wireless link performance analysis results showed that receiver sensitivity was $-56{\sim}-46\;dBm$ over bandwidth of $5{\sim}50\;GHz$ and antenna gain was calculated to be $26.6{\sim}31.6\;dBi$ at link distance of 10m under the BPSK modulation scheme. The maximum achievable data rates were estimated to be 30, 16 and 12 Gbps at the carrier frequencies of 220, 300 and 350 GHz, respectively, under the A WGN and LOS conditions, where it was assumed that the output power of the transmitter is -15 dBm and link distance of 1 m with BER of $10^{-12}$. If the output power of transmitter is increased, the more higher data rate can be achieved than the above results.